The present disclosure relates to an active front steering (AFS) system for a vehicle.
The AFS system changes a ratio of a target steering angle to an input steering angle of a driver, according to the change of vehicle speed. The ratio is referred to as a steering ratio. When the vehicle is operated at low speed, the AFS system increases the target steering angle with respect to the input steering angle and thus secures operational convenience. Furthermore, when the vehicle is operated at high speed, the AFS system decreases the target steering angle with respect to the input steering angle, and thus secures high-speed straight traveling stability.
As a result, when the vehicle is operated at low speed, the AFS system applies a relatively large amount of steering even though a driver slightly turns the steering wheel, thereby increasing operational convenience. On the other hand, when the vehicle is operated at high speed, the AFS system applies a relatively small amount of steering even through a driver significantly turns the steering wheel. The related technology of the present invention is disclosed in Korean Patent Laid-open Publication No. 10-2010-0138259 published on Dec. 31, 2010.